A Continuation of X-ray diffraction studies on the crystalline form of the enzyme, phosphoglucomutase, as well as primary sequence studies is proposed. These should provide data that will allow the construction of a structural model of the enzyme accurate to atomic resolution. The structure of the enzyme will be compared with structures of other enzymes--particularly those that catalyze - PO3 transfer processes. Studying the binding of substrate or product molecules at the active site of the crystalline enzyme, also by X-ray diffraction techniques, should allow the the catalytic mechanism of the enzyme to be defined. Nuclear magnetic resonance studies of the relationship between the bound metal-ion activator and the -PO3 group that is transferred during the catalytic process should help to define the role of the metal ion in this process. A study of possible conformational changes in the enzyme glucose 1,6-bisphosphate synthase, during substrate processing will be initiated in an attempt to relate these changes to analogous changes that appear to occur in phosphoglucomutase. Studies on factors which influence the crystallization of proteins also will be continued as well as studies utilizing endogenous phosphoglucomutase as a metal ion indicator to assess the concentration of free Zn2 ion in serum.